Generally, to cope with a danger of air pollution and petroleum depletion, related technologies for an environmentally friendly vehicle using electric energy as power of the vehicle has been actively developed. The environmentally friendly vehicle includes a hybrid electric vehicle, a fuel cell electric vehicle, and an electric vehicle.
A vehicle according to the related art uses a hydraulic electric driving system, while the environmentally friendly vehicle including the motor-driven electric driving system is recently being released. The motor-driven electric driving system attaches a 3-phase brushless AC motor (hereinafter, referred to as a BLAC motor) to a steering link part to directly transfer power. The hydraulic electric driving system according to the related art has more reduced performance than the motor-driven electric driving system in view of the improvement in fuel efficiency of the vehicle. Since the motor-driven electric driving system does not use power of an engine at all while performing an operation to assist a steering force for a driver, the motor-driven electric driving system may increase the fuel efficiency of the vehicle as much as 3 to 5%, compared with the hydraulic electric driving system.
Meanwhile, as the motor used in the motor-driven electric driving system, a DC motor or the BLAC motor may be used. The BLAC motor in which components corresponding to a brush and a commutator in the DC motor according to the related art are replaced with a semiconductor switch has been used. According to the related art, to determine whether the BLAC motor is normally operated and controlled, a control state of the BLAC motor is determined by measuring a current flowing in an A-phase line and a B-line line, which are connected between an inverter and the BLAC motor, by each of the current sensors and comparing the measured current values.
FIG. 1 is a schematic diagram illustrating an apparatus for controlling a 3-phase brushless AC motor according to the related art. Referring to FIG. 1, an apparatus 100 for controlling a 3-phase brushless AC motor according to the related art includes a control unit 110, an inverter 120, a current sensor unit 130 (130a and 130b) for control, a current sensor unit 140 (140a and 140b) for monitoring, and a BLAC motor 150.
The inverter 120 controls a driving of the BLAC motor 150 by a vector control mode depending on a received PWM signal. The inverter 120 receives, as a feedback signal, an electrical angular speed signal of a motor rotation angle measured by a rotor speed sensor (not illustrated) included in the BLAC motor 150 at the time of driving the BLAC motor 150 to control a magnetic flux component and a torque component, thereby controlling the driving of the BLAC motor 150.
The current sensor unit 130 (130a and 130b) for control includes a first A-phase current sensor 130a configured to measure a current flowing in an A-phase line connecting between the BLAC motor 150 and the inverter 120 and a first B-phase current sensor 130b configured to measure a current flowing in a B-phase line connecting between the BLAC motor 150 and the inverter 120.
The first A-phase current sensor 130a measures the A-phase current of a motor stator which is the current flowing in the A-phase line to generate a current measurement signal ias1 for A-phase control of the stator which represents an A-phase current value of the stator.
The first B-phase current sensor 130b measures the B-phase current of the motor stator which is the current flowing in the B-phase line to generate a current measurement signal ibs1 for B-phase control of the stator which represents a B-phase current value of the stator.
The current sensor unit 130 (130a and 130b) for control transfers the current measurement signal ias1 for A-phase control of the stator output from the first A-phase current sensor 130a and the current measurement signal ibs1 for B-phase control of the stator output from the first B-phase current sensor 130b to a first rotor coordinate system unit 111 which is included in the control unit 110.
The current sensor unit 140 (140a and 140b) for monitoring includes a second A-phase current sensor 140a configured to measure the current flowing in the A-phase line connecting between the BLAC motor 150 and the inverter 120 and a second B-phase current sensor 140b configured to measure the current flowing in the B-phase line connecting between the BLAC motor 150 and the inverter 120.
The second A-phase current sensor 140a measures the A-phase current of the motor stator which is the current flowing in the A-phase line to generate a current measurement signal ias2 for A-phase monitoring of the stator which represents the A-phase current value of the stator.
The second B-phase current sensor 140b measures the B-phase current of the motor stator which is the current flowing in the B-phase line to generate a current measurement signal ibs2 for B-phase monitoring of the stator which represents the B-phase current value of the stator.
The current sensor unit 140 (140a and 140b) for monitoring transfers the current measurement signal ias2 for A-phase monitoring of the stator output from the second A-phase current sensor 140a and the current measurement signal ibs2 for B-phase monitoring of the stator output from the second B-phase current sensor 140b to a second rotor coordinate system unit 112 which is included in the control unit 110.
The BLAC motor 150 is driven by controlling the inverter 120.
The control unit 110 is an electronic control unit (hereinafter, referred to as ECU) included in the motor-driven electric driving system which is mounted in the vehicle and controls an operation of each component of the apparatus 100 for controlling a 3-phase brushless AC motor.
The control unit 110 includes a first rotor coordinate system transformation unit 111, a second rotor coordinate system transformation unit 112, and a current sensor abnormality determination unit 113.
The first rotor coordinate system transformation unit 111 performs coordinate transformation on the current measurement signal ias1 for A-phase control of the stator and the current measurement signal ibs1 for B-phase control of the stator received from the current sensor 130 (130a and 130b) for control to generate a current measurement signal irds1 for D-axis control of the rotor coordinate system and transfer the generated current measurement signal irds1 for D-axis control to the current sensor abnormality determination unit 113.
Further, the first rotor coordinate system transformation unit 111 performs coordinate transformation on the current measurement signal ias1 for A-phase control of the stator and the current measurement signal ibs1 for B-phase control of the stator which are received from the current sensor 130 (130a and 130b) for control to generate a current measurement signal irqs1 for Q-axis control of the rotor coordinate system and transfer the generated current measurement signal irqs1 for Q-axis control to the current sensor abnormality determination unit 113.
The second rotor coordinate system transformation unit 112 performs coordinate transformation on the current measurement signal ias2 for A-phase monitoring of the stator and the current measurement signal ibs2 for B-phase monitoring of the stator which are received from the current sensor 140 (140a and 140b) for monitoring to generate a current measurement signal irds2 for D-axis monitoring of the rotor coordinate system and transfer the generated current measurement signal irds2 for D-axis control to the current sensor abnormality determination unit 113.
Further, the second rotor coordinate system transformation unit 112 performs coordinate transformation on the current measurement signal ias2 for A-phase monitoring of the stator and the current measurement signal ibs2 for B-phase monitoring of the stator which are received from the current sensor 140 (140a and 140b) for control to generate a current measurement signal irqs2 for Q-axis monitoring of the rotor coordinate system and transfer the generated current measurement signal irqs2 for Q-axis monitoring to the current sensor abnormality determination unit 113.
The current sensor abnormality determination unit 113 receives the current measurement signals irds1 and irqs1 for D-axis and Q-axis control from the first rotor coordinate system transformation unit 111 and generates the current measurement values for D-axis and Q-axis control from the received current measurement signals irds1 and irqs1 for D-axis and Q-axis control.
Further, the current sensor abnormality determination unit 113 receives the current measurement signals irds2 and irqs2 for D-axis and Q-axis monitoring from the second rotor coordinate system transformation unit 112 and generates the current measurement values for D-axis and Q-axis monitoring from the received current measurement signals irds2 and irqs2 for D-axis and Q-axis monitoring.
Next, when the current measurement value exceeds a preset threshold value by comparing the generated current measurement values for D-axis and Q-axis control with the current measurement values for D-axis and Q-axis monitoring, the current sensor abnormality determination unit 113 may determine that at least one of the current sensors included in the current sensor unit 130 (130a and 130b) for control and the current sensor unit 140 (140a and 140b) for monitoring is in a fault (abnormal) state and generate and output a sensor abnormal signal representing that at least one of the current sensors is in the fault (abnormal) state.
Meanwhile, the apparatus 100 for controlling a 3-phase brushless AC motor according to the related art may not perform a normal driving control of the BLAC motor 150 when at least one of the included current sensors is in the fault (abnormal) state.
Further, the sensor abnormal signal which is generated and output by the control unit 110 of the apparatus 100 for controlling a 3-phase brushless AC motor according to the related art may not confirm which sensor among the included current sensors is in the fault (abnormal) state. Therefore, only when the input and output of each sensor are checked to find out and replace the sensor in the fault (abnormal) state or replace all the sensors, the normal driving control of the BLAC motor 150 may be realized.
Further, the apparatus 100 for controlling a 3-phase brushless AC motor according to the related art may perform the normal driving control of the BLAC motor 150 when at least one of the included current sensors is in the fault (abnormal) state while the vehicle is driven and thus may not assist a steering force for a driver, thereby increasing a danger of accident.
When the current sensors used to determine the operation and control state of the BLAC motor used in the motor-driven electric driving system according to the related art are in a fault condition, the operation of the BLAC motor may not be controlled and thus the motor-driven electric driving system is also normally operated. When the motor-driven electric driving system is in a fault condition while a driver drives a vehicle, the operation to assist the steering force may not be assisted and thus the driver may be in danger of accident. Therefore, a need exists for a technology of normally operating the motor-driven electric driving system by controlling the operation of the BLAC motor even though the current sensor used to determine the operation and control state of the BLAC motor used in the motor-driven electric driving system is in a fault state.